Our government called the terror attacks on our country an act of war and replied with a declaration of war on terrorism. What can history teach us about our prospects in such a war?

But this forbearance outlasted the Cold War by more than a decade, and spanned four administrations, each of which announced that America would not tolerate states that sheltered terrorists, and then tolerated them. Why? Perhaps the Cold War-enforced habit of putting up with what would normally be considered acts of war had simply taken root. Perhaps there was a guilty conscience, a hangover from the days of European imperialism, when Western states had regularly taken military reprisals against less-well-armed Asian and African ones. Moreover, our military power so dwarfed that of the Third World states that were provoking us that we may at some level have refused to take even gross insults very seriously. Or perhaps it was the opposite: In the wake of a misperception about the lessons of Vietnam, the terrorist-sheltering states may have seemed rather formidable. Or perhaps it is simply the case that oil, like rank, has its privileges, and the oil states conspicuously sympathized with one brand of terrorism.

Whatever the reasons, by the late 1980s a weak state could wage proxy war against the United States through terrorism, and do so without punishment unless it was caught red-handed, and if it was caught red-handed, the punishment would prove endurable. Now we are pressuring states currently sponsoring or tolerating terrorists to instead take effective measures against them. If we are even partially successful, we may be in for an unpleasant surprise, for this approach refights some very old wars indeed. In the nineteenth and early-twentieth centuries, Western states periodically compelled non-Western states to crack down on homicidal and xenophobic elements within their own societies. They did it with both Qing China and Tokugawa Japan, and the result was to erode the legitimacy of both regimes, which subsequently collapsed.

Pakistan, Egypt, and a number of states on the Arabian Peninsula have fragile regimes that have made uneasy peace with indigenous violent xenophobic movements. We may erode the legitimacy of these regimes if we push them hard, and if we do not push them hard, they will likely remain tolerant of at least some terrorists—certainly of ones who strike at the Israelis, or the Indians, or Americans. And Pakistan is now a nuclear weapons state; if its government collapses, its fission bombs will fall into what may be extremely hostile new hands. Pressing for the nuclear disarmament of Pakistan may be both implausible and risky, while failing to disarm Pakistan may in the lone run be riskier still.

Not all military defeats produce dedicated would-be martyrs; some make the defeated party lose all taste for a fight.

In any case, it seems clear that one war that we should not refight is the halfhearted one against terrorist states. A series of minimal responses to stateabetted terrorism has been cumulatively catastrophic; with each mild retaliation, we have taught such states that it is safe to conduct a policy of covert murder against our country’s civilians. Another war we must hope the administration does not refight is our recent campaign against terror conducted on the model of a criminal investigation and prosecution. Criminal investigations are intensely rule-bound, as they must be. A state waging proxy war is by definition bound by no laws, and combating it with laws is to risk entering a onesided suicide pact. Economic sanctions, for instance, can go on for decades with no noticeably useful effect, and states as weak as Libya, Cuba, and postwar Iraq rarely seem to have been inhibited by them. The World Trade Center, on the other hand, disappeared very quickly.

So which wars might we want to consider refighting? Does the more distant past hold any useful lessons? At first glance, it seems to. For decades, sovereignty has been held as absolute; all states are to be treated as formal equals, on the theory that all states observe minimal norms. But the existence of states practicing genocide at home and/or terrorism abroad suggests that all states are not observing what most Americans consider minimal norms. The norm just broken has cost more American lives than were lost on Omaha Beach.

In the nineteenth century, norm-breaking states were not always treated as formal equals, and they risked the loss of their sovereignty. If we discover that a state has backed grievous assaults on us, should we in fact suspend the sovereignty of that state by force of arms—invasion, conquest, and the formation of a new regime? I think it is worth remembering that such a policy was effected as recently as 1945, and with considerable success. There is no obvious reason why it cannot be done again. There will be many bad consequences if we try and fail, and very probably some if we try and succeed, and not all these consequences can even be imagined before we start. But states are often taught by example.

This is not to imply that we have the power to make a political paradise of some pretty unpromising material. We do not; we ourselves are not a political paradise. If we end by setting up a new regime anywhere, it is not likely to be nearly as successful, or as long-lived, as the postwar regimes of Germany, Japan, and Italy have been. This will be sad for its citizens but will not necessarily make the exercise worthless. The purpose of destroying a rogue regime is not only reprisal but deterrence. This we may be able to achieve, for some reprisals succeed.